A new study of the prairie vole, a rodent species famed for its monogamous ways, has shown that the vole's brain chemistry changes when its mate is taken away, and that it loses some of its vim and vigor. Researchers compared the behavior of males who were separated from either their mates or their siblings, and found that those voles who had lost their loyal mates were passive and unresponsive--maybe even depressed. Prairie voles are one of the few mammals that are generally monogamous; the mates form life-long bonds and rear their pups together. In the new study, researchers subjected all the male voles to stress tests, like dunking them in basins of water and holding them suspended by their tails, and found that the voles whose mates had been spirited away put up less struggle. In the water, for example, they floated listlessly instead of paddling for their lives.
These voles "basically were passive -- they gave up," [study coauthor Larry] Young said. "I would be hesitant to say that these animals were depressed, but their behavior is reminiscent of what you would see in a depressed person" [HealthDay News].
In the study, published in Neuropsychopharmacology [subscription required], researchers also found that the voles that lost their mates had higher blood levels of a stress hormone, suggesting that a neurotransmitter called corticotropin releasing factor (CRF) was more active in these forlorn critters.
"In nature this can be a good thing because this stress response makes them seek out their partner again, helping to maintain a stable relationship.... What we are tapping into here is the flip side of the attachment bond," Young says. "Pleasure sensors of the brain are activated when couples are together but there is another mechanism involved with the stress of being parted" [New Scientist].
Finally, researchers found a way to reverse the effects of the loss and get the lovelorn voles to paddle and struggle energetically again. Voles given a drug that blocked CRF activity showed none of their previous mopey behavior, said study coauthor Oliver Bosch,
suggesting that drugs could do the same in people struggling to overcome the loss of somebody close.... "It might be possible to potentially ease this bereavement and in the future use these blockers to treat patients that are really suffering from losing a partner," he said [Reuters].